Running: Your Guide to Hydration & Dehydration

Ensuring we maintain a good level of hydration has been proven to enhance performance whilst exercising. The muscles and brain require a certain minimum of water and salt for strong and healthy performance.

About Dehydration / How Much to Drink? / What to Drink? / Electrolyte Drinks / Electrolyte Gels / Further Suggestions

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WHAT IS DEHYDRATION?

Dehydration is a condition that occurs when someone loses more fluids than the body is taking in. Hydration is crucially important for anyone of any age.

Our bodies are about two thirds water. When we become dehydrated, it means the amount of water in the body has dropped below the level needed for normal body function. The key factors in dehydration are not only water, but electrolytes, which our bodies lose through sweat during exercise. The main electrolyte is sodium, which is a salt our body naturally produces. We do however rely on other body salts - the body rapidly loses potassium and magnesium through perspiration when we exercise. It is essential we then replace these as quickly as possible to avoid severe dehydration.

What happens when we are dehydrated?

Dehydration will have a direct and negative impact on the body, causing fatigue during earlier stages of exercise. Usually if we are feeling thirsty, that already means we have become dehydrated. As our body becomes dehydrated our blood volume decreases, making it harder for blood to return to our heart. So consequently the less oxygen-rich our blood is reaching our muscles, the more fatigued we become, making it near impossible to maintain a good level of anaerobic exercise.

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HOW MUCH TO DRINK WHILE RUNNING?

Knowing how much you need to drink per hour of exercise is the challenging bit. Research suggests that we need between 300-800ml of liquid per hour, depending on conditions and the individual. That is a large margin of difference, so how to narrow it down?

Firstly, trust your thirst. Then consider the weather. Aim for 300ml in moderate temperatures and 400ml in hotter conditions, but carry more so you can increase if you feel the need. Experiment, write down how much you drink and how you feel in the 24 hours after your run. Check your urine immediately after your run and the next day. Then adjust what you drink next run. If you write down the results you won't be struggling to remember and you will establish exactly what works for you.

The key factors of dehydration are obviously what our bodies lose through perspiration. Sweating during exercise is healthy and perfectly normal! So there is no need to worry, however each individual will have a different sweat rate. This can easily be monitored and calculated by taking your body weight before and after a run or race.

For example, if you lost three pounds during a training run, you would need to drink about 4.5 pounds of fluid (4.5 pints) over the next several hours to be sure that you are fully rehydrated. How much fluid to take on board is also something many of us are often confused about. This is also a very personal part of your regime and again will depend our sweat rate. Sweat rate tends to be the most important factor, but also the conditions, duration, and time of the event will have a major influence on how much fluid we need to consume.

Monitoring what our intake should be will depend on our fluid losses from training and other activities. If we replace less fluid then we have lost each day, then obviously our hydration levels will not be right. The easiest way of monitoring our body's hydration level is to analyse urine colour and quantity. If it is darker and more concentrated, that means you are dehydrated; a paler and less concentrated urine will mean that your body is well hydrated. This is a fantastic guideline leading up to a race, so even the night before you will be able to have a good indication of what your hydration levels are like.

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WHAT TO DRINK WHILE RUNNING?

The key to staying hydrated is not only fluid intake, but also intake of electrolytes – the minerals we lose through sweating. This is especially important when running long distances.

The 3 main key electrolytes are Sodium, Potassium, and Magnesium. These all help the body to function properly. Having an electrolyte-based drink or gel with a high content of these three minerals will aid the body's recovery, and should be comfortably absorbed and digested.

There are essentially two ways to handle this: either with electrolyte drinks, or with a combination of electrolyte gels and plain water. This is down to personal preference, as either will do the job. If you're training for anything from a marathon upwards, it is always a good idea to have tried a couple of alternatives beforehand, to see what your stomach prefers.

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